Use smile format instead of json for internal Druid process communication.

For internal communication between Druid processes, switching to a binary format would provide reduction in bytes transferred over the network and better performance.
This should be done for transferring published segments data between coordinator and broker and possibly at other places.

Start by tracing the internal communication that transfers published segments data between the coordinator and broker, then identify the JSON serialization points involved. Check whether other Druid process-to-process communication paths are in scope. Done means the agreed communication paths use Smile and retain the required data exchange behavior.

Written by the indexing model from the issue text.